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Description: fix uninitialized memory when proxying to a malicious FTP server
Author: covener
Origin: upstream, https://svn.apache.org/viewvc?view=revision&revision=1873745
Bug: https://security-tracker.debian.org/tracker/CVE-2020-1934
Forwarded: not-needed
Reviewed-By: Xavier Guimard <yadd@debian.org>
Last-Update: 2020-08-25
--- a/modules/proxy/mod_proxy_ftp.c
+++ b/modules/proxy/mod_proxy_ftp.c
@@ -218,7 +218,7 @@
* (EBCDIC) machines either.
*/
static apr_status_t ftp_string_read(conn_rec *c, apr_bucket_brigade *bb,
- char *buff, apr_size_t bufflen, int *eos)
+ char *buff, apr_size_t bufflen, int *eos, apr_size_t *outlen)
{
apr_bucket *e;
apr_status_t rv;
@@ -230,6 +230,7 @@
/* start with an empty string */
buff[0] = 0;
*eos = 0;
+ *outlen = 0;
/* loop through each brigade */
while (!found) {
@@ -273,6 +274,7 @@
if (len > 0) {
memcpy(pos, response, len);
pos += len;
+ *outlen += len;
}
}
apr_bucket_delete(e);
@@ -385,28 +387,35 @@
char buff[5];
char *mb = msgbuf, *me = &msgbuf[msglen];
apr_status_t rv;
+ apr_size_t nread;
+
int eos;
- if (APR_SUCCESS != (rv = ftp_string_read(ftp_ctrl, bb, response, sizeof(response), &eos))) {
+ if (APR_SUCCESS != (rv = ftp_string_read(ftp_ctrl, bb, response, sizeof(response), &eos, &nread))) {
return -1;
}
/*
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, NULL, APLOGNO(03233)
"<%s", response);
*/
+ if (nread < 4) {
+ ap_log_error(APLOG_MARK, APLOG_INFO, 0, NULL, APLOGNO(10229) "Malformed FTP response '%s'", response);
+ *mb = '\0';
+ return -1;
+ }
if (!apr_isdigit(response[0]) || !apr_isdigit(response[1]) ||
- !apr_isdigit(response[2]) || (response[3] != ' ' && response[3] != '-'))
+ !apr_isdigit(response[2]) || (response[3] != ' ' && response[3] != '-'))
status = 0;
else
status = 100 * response[0] + 10 * response[1] + response[2] - 111 * '0';
mb = apr_cpystrn(mb, response + 4, me - mb);
- if (response[3] == '-') {
+ if (response[3] == '-') { /* multi-line reply "123-foo\nbar\n123 baz" */
memcpy(buff, response, 3);
buff[3] = ' ';
do {
- if (APR_SUCCESS != (rv = ftp_string_read(ftp_ctrl, bb, response, sizeof(response), &eos))) {
+ if (APR_SUCCESS != (rv = ftp_string_read(ftp_ctrl, bb, response, sizeof(response), &eos, &nread))) {
return -1;
}
mb = apr_cpystrn(mb, response + (' ' == response[0] ? 1 : 4), me - mb);
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